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Lower vitamin b12 absorption levels due to a MTHFR gene variant requires supplementing with a methylcobalamin. File photo
ColumnsPatient Advocate

Patient Advocate: Best way to optimize B12 absorption

My first job as a clinician required me to administer vitamin B12 shots, and as a result, I saw a lot of people that would mention, “I can only take the methyl version of B12 because I have the MTHFR gene.”

Many times I was not able to go into details. Please allow me to elaborate.

What is B12? B12 is a vitamin that we get from foods such as meat and leafy green vegetables and is critical in constructing genetic material in all human cells.

We could write an entire article on just B12 and implications on our bodies, and perhaps we will, but not in this article.

What is important to know is that many of us have lower absorption rates due to genetic, physiological and biochemical subpar mechanisms and we need to supplement.

We can supplement with methylcobalamin or cyanocobalamin. These are the two types of commercially available B12. We can supplement orally, through injection or added to an IV bag. All routes are not created equal.

MTHFR gene comes into play because it participates in the processing of folate and the regulation of homocysteine.

Adequate folate levels are needed for methylation.

Lower folate levels increase homocysteine levels in the body. Higher homocysteine levels are a risk factor for ischemic stroke, thrombotic and cardiovascular disease.

For people that have an MTHFR variant, methylation mechanisms are down-regulated, and coincidentally supplementing with methylated B12 bypasses the “faulty gene” and gives the body much-needed methyl groups to up-regulate folate and keep homocysteine levels down.

Another important factor, physiologically speaking, is how our bodies come into contact with the most amount of B12  the quickest; intravenously administration accomplishes this, followed by intramuscular and oral administration.

This is true for B12 absorption, but it is not true for every substance. 

Furthermore, continuous intake of B12 whichever the route does not necessarily mean higher numbers.

The body will dump excess B12 into the urine to avoid intoxication, and higher numbers do not necessarily mean higher functioning “genes.”

What is important to know is that genes are just part of the story.

You should be supplementing with a methylated B12,  however, dosing is dependent on your blood levels.

A blood test, correlated with certain symptoms gives a baseline for proper supplementation.

The route of administration have different absorption rates and should be considered when optimizing levels.

Dr. Sadi Jimenez is a naturopathic doctor who practices integrative medicine in Carlsbad. For a consultation, please visit her website here